シールド工法における掘進障害土層の地質要因とその調査

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In this report, investigation on the soil character of strata causing difficulties in driving which should have been carried out before the commencement of the excavation by the tunnel shield have been studied by the past tunnelling experiences. As the tunnel shield driving safely in the soft ground should have equipment or measures to secure the safety of the tunnel face and to prevent the ground settlement, the soil investigation should have a great weight in the choice of the construction method. If we stands a position to prevent the tunnel face from its collapse, the blind type tunnel shield attracts our attention and also for measures to be taken for the ground settlement, the balancing of the driving power, excavated material mucking speed and opened area of the shield bulkhead is required. The difficulty in driving a tunnel by the blind type tunnel shield is caused by the presence of sand stratum or very hard clay stratum. From tunnel excavation experiences by the blind type tunnel shield or blind type mechanical tunnel shield equipped with auger, it was found that there was the occupancy limit of such strata at each part of the tunnel face. For instance, in case that the blind type tunnel shield at Soka shown in Fig. 7 encountered such strata at top part of the tunnel face, the occupancy limit was approximately 14%. The soil investigation for the tunnel shield work are carried out the planning and designing stage and the additional soil investigation is made at the construction stage. The items and accuracy of the soil investigation are determined according to the requirement of each stage. The tunnel shields or supplementary measures have the extent of soil suitable to each of their types or measures. Generally, as the extent of suitable soil overlaps by each types of measurs, the conclusion from the soil investigation and its result influences success of construction work. Judging from the thickness of such strata causing the difficulties in driving, if it is possible to know the presence of such strata in the accuracy of the order of 10cm or 20cm in thickness, no problem will be cocurred. But a careful attention should be paid to the fact that the stratum thickness may vary largely even though in a short distance.
一般社団法人日本応用地質学会の論文
1981-06-30

著者

小林健郎
前田建設工業(株)

シールド工法における掘進障害土層の地質要因とその調査

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